Python的學習筆記案例8--空氣質量指數計算8.0

前面一節講過獲取所有的城市的AQI，僅僅是將獲取的AQI輸入，並沒有保存，這節課重點講如何將獲取的AQI保存到本地的CSV文件。

"""
    作者：lanxingbudui
    日期：2020-03-04
    功能：AQI計算
    版本：8.0
"""

import requests
from bs4 import BeautifulSoup
import csv


def get_city_aqi(city_pinyin):
    """
        獲取一個城市的所有AQI指標
    """
    url = 'http://pm25.in/' + city_pinyin
    r = requests.get(url, timeout=30)  # 鏈接網頁請求
    # print(r.status_code)  # 打印返回結果，200成功 400失敗
    soup = BeautifulSoup(r.text, 'lxml')  # 創建BeautifulSoup對象
    div_list = soup.find_all('div', {'class': 'span1'}) # 查找所有spen1屬性的節點
    # 或者 = soup.find_all('div', class_ = 'spanl')  # 不推薦這樣寫，因爲class是關鍵字，有時容易忘記下劃線。

    city_aqi = []
    for i in range(8):
        div_content = div_list[i]
        caption = div_content.find('div', {'class': 'caption'}).text.strip()
        value = div_content.find('div', {'class': 'value'}).text.strip()
        # .text是獲取屬性值，並且.strip()移除上步驟中 text 字符串頭尾的空格或換行符
        city_aqi.append( value)
    return city_aqi


def get_all_cities():
    """
        獲取所有城市
    """
    url = 'http://pm25.in/'
    city_list = []
    r = requests.get(url, timeout=30)  # 鏈接網頁請求
    soup = BeautifulSoup(r.text, 'lxml')  # 創建BeautifulSoup對象
    city_div = soup.find_all('div', {'class': 'bottom'})[1]
    # <a href="/abazhou">阿壩州</a> 獲取類似這一段的內容，取所有的城市
    city_link_list = city_div.find_all('a')
    for city_link in city_link_list:
        city_name = city_link.text  # 獲取value值---阿壩州
        city_pinyin = city_link['href'][1:] # 獲取hrdf的屬性值 --/abazhou 並消去/
        city_list.append((city_name, city_pinyin))
    return city_list


def main():
    """
        主函數
    """
    city_list = get_all_cities()
    # for city in city_list:
    #     city_name = city[0]
    #     city_pinyin = city[1]
    #     city_aqi = get_city_aqi(city_pinyin)
    #     print(city_name, city_aqi)
    header = ['City', 'AQI', 'PM2.5/1h', 'PM10/1h', 'CO/1h', 'NO2/1h', 'O3/1h', 'O3/8h', 'SO2/1h']
    with open('china_city_aqi.csv', 'w', encoding='utf-8', newline='') as f:
        writer = csv.writer(f)
        writer.writerow(header)
        for i, city in enumerate(city_list):
            if (i + 1) % 10 == 0:
                print('已處理{}條數據，共{}條數據'.format(i + 1, len(city_list)))
            city_name = city[0]
            city_pinyin = city[1]
            city_aqi = get_city_aqi(city_pinyin)
            row = [city_name] + city_aqi
            writer.writerow(row)


if __name__ == '__main__':
    main()